Case Study
Mill Creek Case Study
Summer 2022
In 2020, a concerned landowner reached out to the District, worried about the increased stormwater he was receiving from the Tanger Outlets and related shopping areas. During a big storm event, his pasture would flood, rendering it unusable for livestock. On top of the landowner’s concerns, the stream on his property, a tributary to Mill Creek, had limited habitat, significant siltation, and eroded banks. The stream and pasture needed help, and stream restoration was the tool the fix it. Using Mill Creek 319 funds from the EPA, we designed, permitted, and constructed a project that would restore the stream and reduce the landowner’s flooding problems.
The landowner’s stream before construction. Notice the eroded stream banks and lack of trees.
“Brush Mattress.” This is great habitat for turtles and birds, among other wildlife.
After the necessary permits and funding were secured, construction began in the spring of 2022. U.S. Fish and Wildlife Services constructed the project, creating some of the following in-stream structures: mudsills, log vanes, riffles, toe logs, and a brush mattress. Each structure helps the stream and the wildlife in its own way. Toe logs and brush mattresses armor the bank from erosion and create woody habitat. Riffles oxygenate the stream, which is important for certain species of bugs and fish. Mudsills armor the bank and create cover for fish so they can hide from predators like birds. In the pasture, a grassed waterway, commonly called a swale, was designed with a rocked outlet to act as a filter for the stream. These structures will convey the stormwater in the pasture in a specific, grassed area so it will slowly reach and outlet to the stream.
After construction was complete, it was time to plant 300 trees along the stream banks and create a 35 ft. average width riparian buffer. Thanks to a team of volunteers and their families from Advanced Cooling Technologies, Inc., the tree buffer was completed on a hot summer evening in June. Shortly after, streambank fencing was added to protect the young trees from pasturing animals.
“Log Cross Vane.” This structure reduces pressure on the outside banks and creates woody in-stream habitat.
Before planting was complete. Trees, tubes, and stakes were set out and ready for volunteers.
After planting and fencing were completed. This section of the stream had an average of 50 ft of trees on the right side.
Final Result
It is an incredible feeling to see a stream transform from polluted and devoid of habitat to a restored stream. And yet, this is just one more project in the books, with more to come in future years. If you would like to be a part of a future tree planting project, please check out our Events page for volunteer opportunities and fill out our contact form. We look forward to hearing from you and restoring more streams in Lancaster.
— Watershed Team at the Lancaster County Conservation District